1. Technical Field
Embodiments of the present invention relate to a radar antenna.
2. Description of the Related Art
A radar is a device that detects the distance and direction of a remote object or target and information on the surroundings of the target by sending beam signals to the target to receive and analyze the reflected waves.
A radar utilizes the linear directionality and reflective characteristics of radio waves, enabling detection unaffected by darkness, rain, snow, and other circumstances that may reduce visibility, and in recent times, radar devices are also being used in automotive vehicles for gathering various information.
While various types of antennas may be used for a radar antenna, a type of antenna typically used is the microstrip patch antenna.
FIG. 1 illustrates the structure of a radar antenna that uses general microstrip patches according to the related art.
Referring to FIG. 1, a general radar antenna according to the related art may include a substrate 108, a ground 110, a transition conductor 100, a feed line 102, a multiple number of patch radiators 104 and a matching element 106.
The transition conductor 100 may serve to electromagnetically join a waveguide with the feed line 102. Although it is not illustrated in FIG. 1, the transition conductor 100 may join with a waveguide, so that feed signals provided from the waveguide may be provided to the feed line 102.
The multiple patch radiators 104 may be joined on either side of the feed line 102. Each patch radiator may have a rectangular form. Each patch radiator 104 may be joined with an angle of 45 degrees to provide a 45-degree polarization.
FIG. 2 is a magnified view of a radiating patch part of the radar antenna illustrated in FIG. 1.
Referring to FIG. 2, a microstrip patch used in a radar antenna can have a certain width (W) and length (L), where the length of the patch can be approximately ½ of the wavelength corresponding to the usage frequency.
In a radar antenna that uses the conventional microstrip patches illustrated in FIG. 1, each microstrip patch may radiate signals independently, and it may be needed to adjust the power radiated for each radiator. For example, it may be necessary to adjust the signal intensities such that the patches at the center portion radiate signals with the highest power while patches further away from the center portion radiate signals with lower power.
Such adjustment of the signal intensity for each radiator can be achieved by adjusting the width (W) of each radiator.
A portion of the feed signals provided through the feed line 102 may be provided to a radiator while another portion may continue traveling through the feed line, and likewise at the next radiator, a portion may be provided to the radiator while another portion may continue traveling, resulting in radiation occurring at each of the radiators.
The end of the feed line 102 may be joined with the matching element 106, where the matching element may provide impedance matching for the radar antenna to prevent the occurrence of reflections for the signals in the feed line.
As such, a radar antenna according to the related art may entail a complicated structure, with rectangular patches joined to the feed line in a slanted form while maintaining their respective widths, and since the widths of the microstrip patches are increased the further downstream they are of the feed line in order to allow for the distribution of the signal intensities, the increase in size where the matching element 106 is formed can make it difficult to maintain a compact structure.
Moreover, with a radar antenna that employs the rectangularly shaped patches according to the related art, the structure for a slant polarization having a particular angle can be difficult to implement, as the rectangular patches have to be slanted in the corresponding polarization angle when joined to the feed line.